San Diego and Southern California Fault Information

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Photo from Wikimedia Commons

Photo from Wikimedia Commons

Most of you probably felt the 7.2 magnitude earthquake that shook on Easter Sunday, April 4th. Luckily, the damage in San Diego was minimal.

Unfortunately, Mexicali wasn’t so lucky, and many fires broke out when gas lines and propane tanks shattered. This recent earthquake was so strong because the epicenter was just over six miles below the earth’s surface, which generated severe surface waves. The 7.2 earthquake was felt from Baja California all the way north to Santa Barbara, and east to Phoenix, AZ. Seismologists say that the quake may have occurred towards the southern area of the San Andreas Fault.

Like the rest of Southern California, San Diego County has several active earthquake faults. An alphabetical index of Southern California’s faults can be found here.

The local faults can be found along the northwest-southeast regions of SD county. The most active faults, from east to west, include the San Jacinto, Elsinore, La Nacion, and Rose Canyon faults onshore and the Coronado Bank, San Diego Trough, and San Clemente faults offshore.

Faults are often traced by natural landmarks, such as river valleys and canyons. Faults are natural products of crustal pressures of different lithospheric plates. The largest earthquake documented in San Diego County was the 5.3 that happened on July 13, 1986 located on the Coronado Bank fault, which is just offshore of Solana Beach.

After the big shaker that hit Haiti, many people have deemed it highly important to be more educated about earthquakes and their causes. Earthquakes are caused by a shift in plate tectonics underneath the earth’s surface. Earthquakes will often have foreshocks, which are smaller shocks that act as precursors to the main shock. Aftershocks always follow the main shock, which many of us felt the night post-7.2. Aftershocks can continue for weeks, months, or even years, all depending on the size and severity of the main shock.

The magnitude of an earthquake is determined by the size of the fault and the amount of slip on the fault. Although there is technology to evaluate and measure the magnitudes of earthquakes, there is still no way to predict them.

However, seismic activity researchers have conducted predictions of the possible largest magnitudes to occur along our local faults: San Jacinto (M6.4 to 7.3), Elsinore (M6.5 to 7.3), Rose Canyon (M6.2 to 7.0), La Nacion (M6.2 to 6.6), Coronado Bank (M6.0 to 7.7), San Diego Trough (M6.1 to 7.7), and San Clemente (M6.6 to 7.7). For more information about faults and earthquakes in San Diego County, click here.

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